Thank you for playing our game! I do think a weak point is the difficulty. It gets faster and harder, and the entrance is more expensive, the more loops you go into the tunnel. We got pretty good at the game and didn't want it to go so fast that people wouldn't be able to play, but we definitely over-tuned it.
Losing (not being able to pay for another trip) also gives you a small ending. We are strongly considering making a new version that fixes issues people bring up and adds a couple of things we really wanted but had to cut due to time. So your feedback will 100% be addressed. Once again, thanks for playing!